This External Power Battery Pack for iphone 4 battery case is an ideal and powerful companion for your endeared iPhone 4G/4S. It acts both as a protective case and also as an excellent external battery pack. The potent built-in 1900 mAh Lithium-ion Polymer battery can be engaged in using the On/Off switch button at your will and it is able to provide additional talk time by up to 6~7 hours for your iPhone4 and stand time by 5 days. This case is stylish and portable with textured Black non-slip finish: 2 in1 battery & Docking as well as provides full body coverage for your iPhone 4G/4S.